Carbon electrode for electric lamps



Patented Feb. 13, 1883.

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(No Model.) v.

J. E. ATWOOD;

CARBON ELEGTRODE POR ELECTRIC LAMPS. No; 272,017.

fit 26444134 Mwiw UNITED STATES PATENT OFFICE.

JAMES E. ATWOOD, OF TROY, NEW YORK, ASSIGNOR TO THEODORE MACE,

OF PLAINFIELD, NEW JERSEY.

CARBON ELECTRODE FOR ELECTRIC LAMPS.

SPECIFICATION forming part of Letters Patent No. 272,017, dated February13, 1883.

Application filed June 19, 1882. (No model.) 1

To all whom it may concern Be it known that I, JAMES E. A'rwoon, ofTroy, in the county of Rensselaer and State of New York, have inventedan Improvement in Carbon Electrodes for Electric Lamps, of which thefollowing is a specification.

Electrodes of carbon in lamps are consumed with rapidity and require tobe replaced. The rapidity of consumption arises considerably fromthe'particles of carbon that break ofi' under the action of the electricarc and fall away. These are a loss and also form a deposit in the lowerpart of the globe or shade around the lamp.

Theohject of my invention is to render the carbon electrodes moredurable by surrounding them witha refractory compound that is notconsumed as rapidly as the carbon itself. Hence the coating will form acup around the lower electrode to confine the particles of car bon andrender said electrodes more durable,

In the drawing I have represented by a sectional view the twocarbonelectrodes as they appear in use.

1 take the ordinary gas-carbon electrode for a lamp and dip it into acompound of the following material to form a coating around the whole oralmost all of the length of the said carbon.

The coating material is made by grinding together old plumbago cruciblesor pots, about eighty parts, with about fifteen parts of clay and fiveparts of glass. These are thoroughly pulverized and mixed and renderedsemi-liquid and of about the ordinary consistency of paint by theaddition of water or other liquid. After the carbon has been-dipped orotherwise coated with this compound it is allowed to dry and is readyfor use. It may be covered with a deposit of copper, if desired.

the conducting material.

electric are are retained and the carbon rendered more durable, and thedeposit of carbon on the globe or shade is lessened.

I am aware that metals have been used as a coating for electric-lampcarbons; but the same are not of a refractory nature and do not form acup around the lower carbon to render the carbon more durable.

By the use of refractory material containing plumbago, clay, and glass,or materials having equivalent properties, the plumbago becomes The clayand glass act togetherthe clay to prevent the glass running down theelectrode, and the glass to form a vitreous covering over the clay toprevent the action of atmosphere on the clay and carbon, causing theformer to boil and the carbon to be liberated and consumed, therebyrendering the carbon very durable and forming a slight cup shape, forthe purposes set forth.

I claim as my invention- The electric-lamp carbons coated with plumbago,clay, and glass, substantially as and for the purposes set forth.

Signed by me this 3d day of June, A. D. 1882.

JAMES E. ATWOOD.

